Impeding the transfer of energy between fluids or reducing the evaporation of liquids is a major concern continually confronting both industry and the public. This is especially true in the chemical and petroleum industries where substantial sums of money are lost yearly due to the evaporation of volatile substances. Moreover, environmentalists persistently importune pertinent government bodies to strictly regulate the industries emitting pollutants and toxins. Thus, evaporation poses both a financial and, more importantly, an environmental burden on industry and society.
In still other instances, evaporation of non-toxic as well as toxic substances is also problematic. In regions permanently subjected to arid weather or areas temporarily experiencing unusual drought conditions, the reduction of evaporation or the control of energy transfer may be critical to the viability of the region. Therefore, the ramifications of liquid evaporation may be far more extensive than merely experiencing economic or environmental damage.
To help alleviate some of the problems discussed herewith, rigid or semi-rigid custom fit covers have been developed to insulate or reduce exposure of the top surface of the liquid from the atmosphere. For example, U.S. Pat. No. 4,109,325 to Shuff discloses an inflatable swimming pool cover system which slows evaporation while simultaneously reducing heat loss.
These covers, however, must be custom fit to effectively cover the appropriate area. Therefore, irregularly shaped surface areas pose problems in themselves. For example, bodies of fluid having sloped sides experience surface area and shape alterations as the fluid level changes. Thus, custom fit covers may no longer properly fit as the fluid level increases or decreases. Further, manufacture and repair are costly and significantly more difficult. Ruptures, alone, may render the rigid as well as semi-rigid covers inoperable or ineffective. Lastly, enormous assistance is required to deploy the cover over the surface and position it properly.
Consequently, systems have been developed which more easily cover irregularly shaped surface areas as well as provide an easier method of deployment. One prior art evaporation and energy transfer reduction approach is to introduce a plurality of floatable devices which collectively cover a substantial portion of the surface area of the liquid body. These systems reduce the surface exposure and, thus, evaporation. Furthermore, the ease of deployment is not bias towards symmetrical shapes; that is, irregularly shaped bodies of fluid are just as easily blanketed as are symmetrical ones.
Typical of such an approach is the device set forth in U.S. Pat. No. 3,998,204 to Fuchs et al. This reference describes a floatable ball having contoured flat surfaces surrounding its equatorial plane. The ball is rigid and contains ballast in its bottom portion so that its flat surfaces are vertically oriented and juxtaposed to each other. When the liquid surface is uniform or non-oscillatory, the collective surface-to-surface engagement between the equatorial planes of these balls provides a substantially gapless or uninterrupted floating ball blanket.
Such an approach, however, becomes problematic when the fluid surfaces are no longer uniform. In large bodies of liquid, weather conditions or natural currents foster undulatory or erratic surface conditions. Moreover, these conditions are easily simulated using artificial means such as machinery or human activity. The difficulties lie when the amplitude of the fluid oscillations surpass the height of the surface-to-surface engagement of the abutting equatorial planes of neighboring balls. In these situations, the gapless surface will be interrupted and the efficiency of the floatable blanket substantially diminished. For example, in Fuchs et al., the equatorial mating plane comprises a rather small surface height because of the physical nature of a sphere. Thus, the system according to Fuchs et al. has its maximum effectiveness only when the fluid surfaces conditions are favorable and substantially uniform. Such conditions are not plausible in larger bodies of fluid which are exposed to environmental elements.
A partial attempt to solve the above-mentioned problem is disclosed in U.S. Pat. No. 4,582,048 to Sorensen. This approach distributes a plurality of coverites which comprise a flexible material enclosing a fluid. Each coverite engages in surface-to-surface contact with its neighboring coverite mutually conforming its flexible wall to that of its neighbors. Thus, the individual units, when conformed, are not homogenous and the blanket is in a constant state of evolution. When used correctly and when confronted with an undulatory fluid surface, the coverites provide a formidable barrier which resists the blanket interruptions which Fuchs et al. fails to address.
The primary drawback of an approach such as is disclosed in Sorensen is that to mutually conform the flexible walls to that of its neighboring coverites, substantial lateral force is required to maintain a gapless, uninterrupted sealed barrier. Accordingly, either a substantial number of coverites must be deployed to overpopulate the liquid surface, thereby creating lateral forces, or a fixed barrier enclosing the deployment area must be constructed to provide the lateral resistance necessary to allow conformity between the flexible walls of neighboring coverites. In other words, without the appropriate lateral force, individual coverites will not mold their flexible walls to that of neighboring coverites. As a result, the system according to Sorensen will ineffectively create a thermal barrier and substantial gaps will exist.
Other prior art evaporation and energy reduction techniques and systems which cumulatively form a barrier are disclosed in U.S. Pat. Nos. 4,749,606; 4,467,786; 4,458,688 and 4,270,232. As is true of the above-mentioned prior art, these devices and techniques suffer barrier breach when confronted with undulatory surface conditions.
Accordingly, it is an object of the present invention to provide an improved device that will reduce surface evaporation and the transfer of energy between fluids by introducing a plurality of buoyant devices to the fluid surface which aggregate and cooperate to form a substantially gapless evaporation barrier at the surface of the fluid.
It is another object of the present invention to provide an improved device for maintaining a substantially gapless and uninterrupted barrier when subjected to undulatory or oscillatory fluid surfaces.
It is still another object of the present invention to provide a device that forms an effective evaporation and energy transfer barrier which requires only minimal lateral forces to keep the barrier intact and substantially gapless.
It is a further object of the present invention to provide a method and device for reducing fluid evaporation and energy transfer which is durable, compact, simple to deploy and construct, easy to maintain, and is economical to manufacture.
The device of the present invention has other objects and features of advantage which will become apparent from and are set forth in more detail in the description of the Best Mode of Carrying out the Invention and the accompanying drawing.